[EmojiSuggest] Add record user action

Record user action when an emoji is suggested to get timestamp.
This is to figure out if some users get emoji suggested in a short
timespan.

Bug: b/168692236
Change-Id: I5ceb7c3c1846b9cae5a3c44a0ccc0bf62b7cb756
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2434186
Commit-Queue: My Nguyen <myy@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Jing Wang <jiwan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811494}

chrome/browser/chromeos/input_method/assistive_suggester.cc

@@ -8,6 +8,7 @@
 #include "base/feature_list.h"
 #include "base/hash/hash.h"
 #include "base/metrics/histogram_functions.h"
+#include "base/metrics/user_metrics.h"
 #include "base/strings/string_util.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/browser_finder.h"
@@ -360,6 +361,8 @@ void AssistiveSuggester::RecordAssistiveMatchMetrics(const base::string16& text,
       // Emoji suggestion match
     } else if (emoji_suggester_.ShouldShowSuggestion(text_before_cursor)) {
       RecordAssistiveMatchMetricsForAction(AssistiveType::kEmoji);
+      base::RecordAction(
+          base::UserMetricsAction("InputMethod.Assistive.EmojiSuggested"));
       RecordAssistiveDisabledReasonForEmoji(GetDisabledReasonForEmoji());
     }
   }

tools/metrics/actions/actions.xml

@@ -7613,6 +7613,14 @@ should be able to be added at any place in this file.
   </description>
 </action>
 
+<action name="InputMethod.Assistive.EmojiSuggested">
+  <owner>myy@chromium.org</owner>
+  <owner>essential-inputs-team@google.com</owner>
+  <description>
+    Recorded when users type some words and an emoji is suggested.
+  </description>
+</action>
+
 <action name="InputMethodOptions_Open_chewing">
   <obsolete>
     IMEs have since become extensions and no longer available as predetermined